Issue Date: November 22, 1995
Revision Date: January 12, 2015
Test, Version 1.0 (Vacuum Test)
NON-VOLUMETRIC TANK TIGHTNESS
TEST METHOD (ULLAGE)
||Leak rate of 0.1
gph with PD = 100% and PFA = 0%.
||A tank system
should not be declared tight when an increase in the acoustic noise level
(above background) of the tank under vacuum is detected due to air or
aviation fuel, fuel oil #4. .
volume is 15,000 gallons.
Microphone should be located within 24 feet of all points within the
||None if test is
conducted after the under filled tank test.
||Minimum of 1
There must be no dispensing or delivery during test.
||Vacuum of 1 psi
must be maintained in ullage.
If vacuum cannot be maintained, see manufacturer's instructions.
is independent of product temperature.
||Depth to the
groundwater in tank excavation backfill must be determined.
If groundwater is above product level, vacuum must be adequate to detect
an ingress of groundwater.
||Sensors must be
calibrated before each test in accordance with manufacturer's
systems must be isolated prior to test. Evaluated using unleaded
Tests only ullage portion of tank.
Product-filled portion of tank must be tested using an underfill test
Microphone was 24 feet away from the leak source during evaluation.
Headphones are used during test to listen for the signal of air
Noise signals are tape recorded (not digitally recorded).
Test method may not be effective in some tank excavation backfill (such as
clay) because it may plug holes in tank.
If soil is saturated with product, air or water ingress may not be
declared by vacuum test.
A well point in tank excavation backfill may help identify presence of
Evaluator: United States Testing Co. Inc.
3726 Park Place
Montrose, CA 91020
Tel: (818) 301-7777